Conventionally, there has been publicly known a technique of a turbocharger bearing housing provided in an internal combustion engine. Such a technique of a turbocharger bearing housing is disclosed, for example, in Japanese Patent Application Laid-Open No. H9-310620.
The turbocharger bearing housing rotatably supports a shaft connecting a turbine driven by exhaust gas and a compressor for compressing intake air. Further, the bearing housing is formed with a cooling water passage for circulating cooling water and a lubricating oil passage for supplying lubricating oil to the shaft.
Such a bearing housing is manufactured by casting using cast iron. Further, in the case where the bearing housing is manufactured by casting, the cooling water passage and the lubricating oil passage can be formed simultaneously by using a predetermined core.
However, in the case where the cooling water passage and the lubricating oil passage are formed by using the core as described above, there is a necessity to manufacture the core separately. Thus, it has a disadvantage of increasing the cost.